CHATTANOOGA, Tenn. (WWJ/AP) – Parents of some of the children who survived a deadly school bus crash in Chattanooga are starting to shed some light on the moments leading up to the crash, which killed five kids and injured more than 20 others.

CBS News Correspondent Mark Strassmann spoke to a mother who had three children on the bus, one of whom died. The mother says that her other two children told her that just before the crash, the bus driver asked the children if they were ready to die.

“The mother says that in the moments before the crash, the bus driver said something to the effect of ‘Are you all ready to die?’ and then seconds later, the bus was on its side and five kids were killed,” said Strassmann.

The 24-year-old bus driver, Johnthony Walker, was arrested and charged with five counts of vehicular homicide, reckless driving and reckless endangerment.

Investigators are looking at speed “very, very strongly” as a factor in the crash, Chattanooga Police Chief Fred Fletcher said earlier. An arrest affidavit posted online by Chattanooga station WTVC says Walker was driving well above the posted 30 mph speed limit on a narrow, winding road. His bond was set at $107,500, according to the affidavit.

Police said overnight that five children were killed in the crash. Earlier Monday, Hamilton County District Attorney Neal Pinkston told news outlets the crash killed six. The Associated Press was not immediately able to reach officials Tuesday morning to explain the discrepancy.

Names of those killed have not yet been released; three were in the fourth grade, one was in first grade and one was in kindergarten.

Thirty-five students from kindergarten through fifth grade were on board when the bus flipped onto its side and wrapped around a tree. The bus was the only vehicle involved in the crash, but Fletcher said the scene was complicated and covered a significant area. He also said a warrant had been issued to remove the bus’ black box, which contains data about the vehicle’s movement.

Bloodied Woodmore Elementary School students lay on stretchers, while others walked away dazed with their parents after the crash, local news outlets reported. More than 20 children went to hospitals for their injuries, according to Fletcher.

Emergency responders needed almost two hours to get all the children off the bus.

Television cameras showed emergency vehicles still there late into the night, and the National Transportation Safety Board tweeted that a team would be heading to Chattanooga on Tuesday morning to investigate.

Craig Harris, a parent of two children who were on the bus, told ABC’s “Good Morning America” Tuesday morning he thought the bus driver sometimes drove too fast.

“There has been times where I’ve seen him going a little faster than he probably should be going,” Harris said.

Harris said his daughter and stepson were in shock and pain after the crash but were doing better Tuesday morning.

Television stations reported that people lined up to donate blood and some donors were asked to make appointments for Tuesday.

Kirk Kelly, interim superintendent for Hamilton County schools, said classes would be held Tuesday with counselors available for students and staff.

Fletcher said the families of the children who died had been notified but police would not release their names because they were juveniles.

“Our hearts go out, as well as the hearts of all these people behind me, to the families, the neighborhood, the school, for all the people involved in this, we assure you we are doing everything we can,” Fletcher said.

At the state Capitol in Nashville, Tennessee Gov. Bill Haslam called the crash “a tragic event” and offered assistance.

“We’re going to do everything we can to assist in any way,” Haslam said. “It’s a sad situation anytime there’s a school bus with children involved, which there is in this case.”